Uhm, as far as I know the right upper spot would be the ONLY safe spot, where the tentacles can't reach you and thethings he shoot can't either, from there you got down infront of his beak where the thing comes out then and shoot at it... I think I was busy about a half hour with this boss and he really used up all my healing items, i bealieve I even ran away to find some healing plants at that time, simple because I was caught by the tantacle too much.
But yeah, I also disliked that miniboss.